1. Field of the Invention
The present invention relates to a golf club head and, more particularly, to a technique for improving an impact sound.
2. Description of the Related Art
Techniques for improving an impact sound by appropriately designing the hollow body construction have been proposed in hollow golf club heads typified by a driver head. For example, Japanese Patent Laid-Open Nos. 11-155982 and 2003-275345 disclose techniques for improving an impact sound by partially varying the thickness of a sole portion. Also, Japanese Patent Laid-Open Nos. 2002-186691 and 2003-102877 disclose techniques for improving an impact sound by providing a rib in a sole portion.
Since the volume of a hollow golf club head has been increasing every year, the crown portion and sole portion of the hollow golf club head are becoming thinner, while their areas are increasing together with this trend. Thus, a low-pitched impact sound is more likely to be generated when a golf ball is struck. Under the circumstance, golfers who prefer high-pitched impact sounds want golf club heads that generate higher-pitched impact sounds. Partially varying the thickness of a sole portion produces a certain effect of increasing the pitch of an impact sound, as disclosed in Japanese Patent Laid-Open Nos. 11-155982 and 2003-275345. Providing a rib in a sole portion also produces a certain effect of increasing the pitch of an impact sound, as disclosed in Japanese Patent Laid-Open Nos. 2002-186691 and 2003-102877. These techniques increase the pitch of an impact sound by increasing the degree of constraint of the sole portion. However, as the degree of constraint of the sole portion increases, an impact sound is more likely to be less loud and have poor resonance.